Dose Escalation Study With Bispecific Antibodies in Adult Participants With Lupus Nephritis

This study is researching a particular group of experimental drugs administered for a short period in the treatment of participants with Lupus Nephritis (LN). The main aim of the current study is to see how safe and tolerable the study drugs are in a long-term follow-up. This is a main study, called an umbrella study, which includes several independent smaller sub-studies. Each of these smaller main sub-studies tests different drugs at the same time, all aimed at treating LN. The study is looking at several other research questions, including: * What side effects may happen from taking the study drug * How much study drug is in the blood at different times * Whether the body makes antibodies against the study drug (which could make the drug less effective or could lead to side effects)